Packet fragmentation is an inherent behavior of data transport in IP networks. A packet is a block of data with a strict upper limit on block size that carries with it sufficient identification necessary for delivery to its destination. Fragmentation is the process of breaking a packet into smaller pieces (fragments) so that they will fit into the frames of the underlying network. Upon receiving the fragments, the destination system reassembles the fragments into the original packet. The term MTU (maximum transmission unit) refers to the maximum amount of data that can travel in a frame. In other words, the MTU is the largest packet that can be sent through the network along a path without requiring fragmentation. Different networks have different MTU sizes, so packets may need to be fragmented in order to fit within the frames of the network that they transit.
Deep Packet Inspection (DPI) technology is well known in the art and is often utilized to monitor and troubleshoot IP networks. Typically, DPI systems inspect network traffic and display network addresses of the network traffic when a network event is detected. In addition, some DPI systems can also analyze traffic and determine application information associated with a network address (e.g., chat applications, audio and video applications, etc.). In a network using Internet Protocol Suite (TCP/IP), for example, a DPI system may provide IP addresses of traffic flow when a network event is detected. Using DPI method, to understand the behavior of IP networks, it is necessary to examine each packet. To collect useful information from the packets, a monitoring system typically needs to stitch (reassemble) the fragmented packets together in a highly reliable yet highly efficient manner.